1. Field of the Invention
This invention relates to magazine-fed, recoil-operated automatic and semi-automatic firearms, and more particularly to firearms of this type, having the barrel fixed rigidly to the frame. Still more particularly it relates to an improved slide locking mechanism for such firearms.
2. Prior Art
In automatic and semi-automatic pistols a number of cartridges are carried within a removeable magazine or clip which is inserted into the handle or grip of the weapon. When the weapon is fired, a sliding member mounted on the frame over the barrel and firing chamber is driven rearwardly by recoil to withdraw the spent cartridge from the firing chamber and eject it from the weapon. The sliding member is then returned to the battery position by a recoil spring and is adapted to strip the succeeding round from the magazine and insert it into the firing chamber in readiness for firing.
Almost instantly following the impact of the firing pin with the primer in the cartridge, the propellent powder within the cartridge case is ignited and the resultant high pressure gases drive the bullet or projectile through the barrel toward the muzzle. The gases generated by a modern 0.45 calibre cartridge reach pressures of the order of 18,000 p.s.i. to 22,000 p.s.i. before the bullet or projectile clears the muzzle. It is the recoil opposing the thrust of these gases against the bullet which opens the slide member in weapons of this type. Over the years a great many ingenious systems have been devised to prevent the premature opening of the slide with its attendant potentially disasterous results.
The most commonly used mechanisms for holding the action closed during the period in which the gases are at a pressure considered unsafe are those in which some locking means are contrived to hold the barrel together with the breech face of the slide so that the barrel and slide or breech face move rearwardly under the influence of recoil locked together as a single unit. When the gas pressure has reached a safe level, one of several mechanisms is utilized to unlock the slide from the barrel, thus allowing the slide to go into full recoil while the barrel returns to battery or some other position.
Unquestionably many of these prior art devices have served their intended functions well. In most cases they have been costly to incorporate within the general design of small arms, however, and many of them have been found to require considerable maintenance. The accuracy of these weapons is known to be adversely affected to some extent by the compound action of the locking mechanism, and to an even greater degree by the attendant disturbance of the axial alignment of the barrel.
To exacerbate these deficiencies, in a number of weapons of this type, the relatively loose tolerances required between the moving parts are such that the compound action reduces accuracy still further.
By way of example, in the case of the well known Colt 0.45 calibre Government Model 1911 semi-automatic pistol to which my invention is readily adaptable, male buttresses and female grooves or annuli lock the slide and barrel together.
While this locking system performs satisfactorily in securing the barrel and slide, unlocking means must be provided to release the two members at a strategically predetermined time following gas pressure peaking. In the Colt pistol this is achieved by connecting the rear end of the barrel to the frame by means of a link, the upper end of which is rotatably attached to a lug on the underside of the breech, and the lower end of which is rotatably attached to the frame. When the weapon is fired, the engaged buttresses and annuli cause the slide and barrel to move rearwardly in recoil as a single unit. As the link rotates about its axis of pivotal attachment to the frame, it draws the breech end of the barrel toward the frame and the buttresses and annuli out of engagement, thereby freeing the slide to move rearwardly to the full recoil position and the barrel to return to its original position at battery. In this particular weapon, disengagement of the barrel and slide is accompanied by a rotational movement of the barrel of the magnitude of 10.degree.-15.degree. from its original sighted alignment.
One object of the subject invention is to provide a small compact firearm which has a fixed barrel and therefore does not rely on such accessory devices as the Colt interlocking buttresses and annuli and rotatable link to prevent the premature opening of the slide. Another object is to provide a locking system for a magazine-fed firearm having a fixed barrel, having a sturdy, durable, effective slide retarding and locking mechanism, which is inexpensive to produce, requires little if any maintenance, and does not impair the accuracy of the weapon.
As will be seen, the subject invention more than satisfies these objects.